Little is known about the response of the cerebrovasculature to acute exercise in children and how these responses might differ with adults. Therefore, we compared changes in middle cerebral artery blood velocity (MCAVmean), partial pressure of end-tidal carbon dioxide (PETCO2), blood pressure and ventilation (VE) in response to incremental exercise between children and adults. Thirteen children [aged 9±1 (SD) y] and 13 sex-matched adults [aged 25±4 y] completed a maximal exercise test during which MCAVmean, PETCO2 and VE were measured continuously. These variables were measured at rest, at exercise intensities specific to individual ventilatory thresholds, and at maximum. Although MCAVmean was higher at rest in children compared to adults, there were smaller increases in children (1-12%) compared to adults (12-25%) at all exercise intensities. There were alterations in PETCO2 with exercise intensity in an age dependent manner (F(2.5,54.5)=7.983, P<.001;η2 =.266), remaining stable in children with increasing exercise intensity (37-39 mmHg; P>0.05) until hyperventilation-induced reductions following the respiratory compensation point (RCP). In adults, PETCO2 increased with exercise intensity (36 to 45 mmHg; P<0.05) until the ventilatory threshold (TVENT). From TVENT to maximum, adults showed a greater hyperventilatory-induced hypocapnia than children. These findings show that the relative increase in MCAVmean during exercise was attenuated in children compared to adults. There was also a weaker relationship between MCAVmean and PETCO2 during exercise in children, suggesting that cerebral perfusion may be regulated by different mechanisms during exercise in the child.
- Cerebral Blood Flow
- Growth and Development
- Copyright © 2017, American Journal of Physiology-Heart and Circulatory Physiology